Image reading apparatus and image reading method

ABSTRACT

An image reading apparatus is provided with an optical reading device for scanning a stationary original placed on a platen to read image on the original; a drive device for moving the optical reading device at the first moving speed and the second or slow moving speed; a detection device for determining a type of image data read by the optical reading device as either the first type, i.e. monotone data, or the second type, i.e. color data; and a scan control device for obtaining and storing image data while scanning a document at the first moving speed. A switching control device switches the drive device to the second moving speed when the detecting device determines the image data read at the first moving speed to be the second type.

BACKGROUND OF THE INVENTION AND RELATED ART STATEMENT

[0001] The present invention relates to an image reading apparatus andan image reading method in which an image on a stationary originalplaced on a platen is scanned and read. The present invention alsorelates to an image reading apparatus and an image reading method forreading an original moving over a platen with an automatic documentfeeder (ADF). More particularly, the present invention relates to animage reading apparatus and an image reading method that are capable ofreading not only a black and white (monotone) original but also a colororiginal.

[0002] In recent years, as more personal computers are used to handlecolor pictures on the internet and electronic photos, there has been anincreasing demand for copying, printing and transmitting color imagesbecause of superior quality as opposed to black and white images. Forthat reason, an image reading apparatus has been required to quicklyread a color original with high quality.

[0003] When an image reading apparatus reads a color original, normallyit is necessary to read image data for each of the three primary colors,namely red (R), green (G) and blue (B). Thus, when reading a colororiginal with the same resolution as a black and white original, theimage reading apparatus has to read at a slower reading speed than thatfor a black and white original.

[0004] A set of originals to be read in the image reading apparatus maycontain both color originals and black and white originals. When theapparatus read such a set of originals using the color mode, a speed ofreading the black and white originals will be dramatically slowed.

[0005] To solve this problem, a conventional apparatus pre-scans anoriginal to determine whether the original is in black and white orcolor. Then, if the original is only in black and white, the imagereading apparatus reads at a high speed in the black and white readingmode. Conversely, if the original is in color, it uses the color readingmode with a slower speed. This system is known as ‘pre-scan/actual scanmethod’.

[0006] In Japanese Patent Publication (KOKAI) No. 09-261417, an imageprocessing apparatus is disclosed as a modified version of the‘pre-scan/actual scan method’ that requires two passes of an original.According to the invention, the reading apparatus is provided with acycling automatic document feeder. It is determined whether the originalis in black and white or color for all documents in advance through aprocess of transporting the originals through a reading position insidethe apparatus. After storing a result of each page of the originals, astationary reading means reads the originals in black and white at ahigh speed scanning. Conversely, a moving reading unit scans and readsthe originals in color placed stationary on a platen to provide a higherquality.

[0007] In Japanese Patent Publication (KOKAI) No. 2001-24850, an imagereading apparatus is provided with a color detection device to determinewhether an original is in black and white or color. Before reading theoriginal, it is selected to read the original in a color reading mode orin a black and white reading mode. The image reading apparatus reads theoriginal only when a result of the color detection device matches to thereading mode.

[0008] However, in the image reading apparatus with ‘pre-scan/actualscan method’ including the one disclosed in Japanese Patent Publication(KOKAI) No. 09-261417, the pre-scan needs to detect whether the originalis in monotone or color in advance of the actual scan to read theoriginals, so it takes longer reading time for the entire originalshaving both monotone and white documents.

[0009] Further, when the apparatus disclosed in Japanese PatentPublication (KOKAI) No. 2001-24850 is set to read in the color mode,monotone originals will not be read if the monotone originals areincluded in a set of the originals. Therefore, it is necessary to resetthe apparatus in the monotone reading mode and read the originals inmonotone one more time. Due to the additional time, the reading time forthe entire set of originals also takes long.

[0010] The first object of the present invention is to provide an imagereading apparatus and an image reading method that can read a set oforiginals containing both color and monotone documents in a shorterperiod of time. The apparatus has a detection function for color andmonotone originals, and reads the monotone documents in a higher speedmode and the color documents in a higher quality mode.

[0011] The second object of the present invention is to provide an imagereading apparatus and an image reading method that has an ADF and canread a set of originals containing both color and monotone documents ina shorter period of time. The apparatus has a detection function for thecolor and monotone originals, and reads the monotone documents in ahigher speed mode and the color documents in a higher quality mode.

[0012] Further objects and advantages of the invention will be apparentfrom the following description of the invention.

SUMMARY OF THE INVENTION

[0013] In order to attain the aforementioned objects, an image readingapparatus of the present invention is provided with an optical readingdevice for scanning a stationary original placed on a platen to readimage; a drive device for moving the optical reading device at the firstmoving speed or the second moving speed; a detection device fordetermining a type of image data read by the optical reading device aseither the first type of data or the second type of data; a scan controldevice for obtaining and storing image data while scanning a document atthe first moving speed; and a switching control device for switching thedrive device to the second moving speed when the detecting devicedetermines the image data read at the first moving speed to be thesecond type of data.

[0014] According to the present invention, the image reading apparatusscans and reads the image data on the stationary original placed on theplaten. When reading the first type of data, for example an image on amonotone original, the image data obtained in the initial readingoperation will be used, thereby eliminating the second scanning.Therefore, it is possible to read a set of originals containing bothmonotone originals and color originals at a higher speed.

[0015] An image reading apparatus of present invention may be providedwith an optical reading device disposed at a predetermined readingposition under a platen for reading a original moving on the platen; atransport device capable of re-feeding the same original to the readingposition; a detecting device for determining a type of image data on theoriginal read by the optical reading device; and a control device forcontrol the other devices. The control device controls the other devicessuch that when the image data is the first type, the image data usingthe first reading mode is output. Further, when the image data is thesecond type, the original is transported (re-fed) to the readingposition to be read the image data again using the second reading modethat is different from the first reading mode.

[0016] According to the present invention, the original may be re-fed tothe reading position after the original is transported in the dischargedirection. It is also perfectly acceptable to feed the original in anupstream direction opposite to the discharge direction, then feed theoriginal back to the reading position again.

[0017] According to the present invention, the image reading apparatusreads the image data on the original being transported by the ADF. Whenreading the first type of data, for example an image on a monotoneoriginal, the image data obtained in the initial reading operation willbe used, thereby eliminating the second scanning. Therefore, it ispossible to read a set of originals containing both monotone originalsand color originals at a higher speed.

BRIEF DESCRIPTION OF THE DRAWINGS

[0018]FIG. 1 is a view showing an image reading apparatus with twocarriages;

[0019]FIG. 2 is a view showing an image reading apparatus with onecarriage;

[0020]FIG. 3(a) is a graph showing a relationship between relativesensitivity and wavelength of color for each sensor, and

[0021]FIG. 3(b) is a graph showing spectral reflectance data of amonotone document;

[0022]FIG. 4 is a diagram of a circuit configuration in an image signalcontrol unit using four line image sensors including a black and whitesensor;

[0023]FIG. 5 is a diagram of a circuit configuration in an image signalcontrol unit using three line image sensors;

[0024]FIG. 6 is a chart showing a reading mode of the image readingapparatus;

[0025]FIG. 7 is a flow chart showing the first operation control methodof the image reading apparatus;

[0026]FIG. 8 is a view showing an image reading apparatus with an ADF;

[0027]FIG. 9 is a view showing a transporting mechanism of the ADF shownin FIG. 8;

[0028]FIG. 10 is a view showing another image reading apparatus with anADF;

[0029]FIG. 11 is a view showing a transporting mechanism of the ADFshown in FIG. 10;

[0030]FIG. 12 is a diagram of a circuit configuration in an image signalcontrol unit using four line image sensors including a black and whitesensor in the image reading apparatus with the ADF;

[0031]FIG. 13 is a diagram of a circuit configuration in an image signalcontrol unit using three line image sensors in the image readingapparatus equipped with the ADF;

[0032]FIG. 14 is a chart showing a reading mode of the image readingapparatus equipped with the ADF;

[0033]FIG. 15 is a flow chart showing the second operation controlmethod of the image reading apparatus; and

[0034]FIG. 16 is a flow chart showing the third operation control methodof the image reading apparatus.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

[0035] Hereunder, embodiments of the present invention will be explainedin detail with reference to the accompanied drawings.

[0036]FIG. 1 is view showing an image reading apparatus with twocarriages according to the first embodiment of the present invention. Asshown in the drawing, a reading portion of an optical reading device iscomposed of the first carriage 50 having a light source 52 and the firstmirror 53, and the second carriage 51 for sending light reflected fromthe first carriage 50 to a photoelectric conversion element 60, such asa CCD via a fixed light condensing lens 56. The optical reading devicehas two carriages to obtain finer image data of an original placed upona platen by maintaining a constant distance of a light path between areading position of the original and the photoelectric conversionelement 60 when the optical reading means moves under the platen to scanand read the original.

[0037] A drive mechanism for driving the two carriages is provided witha slide rail 57 for supporting and guiding the first carriage 50 and thesecond carriage 51, a carriage transport motor 58 and a wire 59. Thewire 59 is interlocked to the reading carriage to transmit a drive forcefrom the motor. When a control device sends a signal to rotate thecarriage transport motor 58 in forward or reverse, the wire 59reciprocally moves as it is trained on a pulley linked to a rotatingshaft of the motor. Thus, the first and the second carriages 50 and 51linked to the wire 59 move and slide in a scanning direction guided bythe slide rail 57. The first carriage 50 can also move in a directionopposite to the scanning direction with a speed that can be varied bythe carriage transport motor 58. In general, a pulse motor controls arotating speed of the carriage transport motor 58 through the number ofimposing pulses.

[0038] The first and second carriages 50 and 51 are configured to beable to scan at a relatively low reading speed corresponding to a colorreading mode and a relatively high reading speed corresponding to ablack and white reading mode. Also, by reversing the rotation of thecarriage transport motor 58, the first carriage 50 can move backward,and return to the starting reading position.

[0039]FIG. 2 is a view showing an image reading apparatus with onesingle carriage according to the second embodiment of the presentinvention. FIG. 2 clearly shows a drive mechanism of an optical readingdevice mounted on one carriage according to the embodiment of theinvention. In this case, the optical reading device, including aphotoelectric conversion apparatus such as a CCD, is arranged in thesingle carriage.

[0040] A carriage transport mechanism according to the embodiment of thepresent invention is provided with a guide rail 79 for supporting andguiding a carriage 61, a carriage transport motor 76, a transport belt75 fixed to the carriage 61 for transmitting a drive force from themotor, and the transmission belt 77 for transmitting a drive force tothe transport belt 75. The carriage 61 is engaged with the transportbelt 75. Therefore, when the carriage transport motor 76 rotates forwardor in reverse, the transmission belts 75 and 77 transmit the rotationalforce of the motor 76 to move the carriage 61. A control device controlsthe carriage transport motor 76 to move and slide the carriage 61 in ascanning direction along the guide rail 79.

[0041] In the case of the one carriage method, similar to the twocarriage method described above, the carriage 61 can move in a directionopposite to the scanning direction and slides at various speedsaccording to a rotating speed of the carriage transport motor 76. Ingeneral, a pulse motor controls a rotating speed of the carriagetransport motor 76 through the number of imposing pulses.

[0042] Thus, the carriage 61 is configured to be able to scan with arelatively low reading speed according to a color reading mode and arelatively high reading speed according to a black and white readingmode. By reversing the rotation of the carriage transport motor 76, thecarriage 61 can move backward, and return to the starting readingposition.

[0043] Next, an image reading method according to the present inventionwill be described in detail. First, a method of determining whether animage is in monotone and color will be explained.

[0044]FIG. 3(a) is a graph showing a relationship between relativesensitivity and wavelength of color for each sensor, and FIG. 3(b) is agraph showing spectral reflectance data of a monotone document. As shownin FIG. 3(a), since each line sensor, R, G and B, has a spectralsensitivity peak at a different wavelength, when reading a colordocument, each line sensor generates maximum output at a differentwavelength. On the other hand, as shown in FIG. 3(b), a monotone (blackand white) document shows a constant spectral reflectance rateregardless of the wavelength. In the figure, each line sensor generatesa constant high output for white pixels and a constant low output forblack pixels. Because of this difference, it is possible to determinewhether an original to be read is either in color or monotone. Note thatsince it is possible to determine color or not by checking the peakwavelength of the line sensor output, even when reading a document athigh speed, this operation becomes possible.

[0045] In this way, a color detection unit (a determining unit) in thisinvention is configured to receive an output from a shading correctionunit (described later) converted into a digital signal at the red, greenand blue line sensors. When there is a difference in the output patternsfrom the sensors, it is determine to be a color document. In the case ofno difference, it is determined to be a black and white document.

[0046] In the next embodiment of the present invention, an image-signalcontrol apparatus (hereinafter referred to as a control apparatus) isprovided a data memory unit 107 (FIG. 4 and FIG. 5) to sequentiallystore image data read by the reading device. Depending on the type ofimage reading apparatus, it is possible to output image data from thereading means, without a data memory to store the image data, to animage forming apparatus after processing correction of the image data.In such a case, in applying the invention, the detection device uses theprocessed signal of the image data from the reading means to determinewhether the image data is in monotone or color.

[0047]FIG. 4 shows a circuit configuration of a control apparatus 100having four line sensors, namely three line sensors of red (R), green(G) and blue (B) and a black and white (B/W) sensor. The controlapparatus 100 shown in FIG. 4 includes an A/D conversion unit 103 toconvert analog data read by the four line sensors 102W, 102R, 102G and102B into digital data; a shading correction unit 104 for correcting ashading of the converted data (sensitivity correction betweenphotoelectric conversion elements); a color detection unit 106 (adetermining unit) for determining a gradation of the shading correcteddata; a control unit 108 for receiving a result determined by the colordetection unit and outputting a signal to control the image readingapparatus; a selector unit 105 for switching and outputting monotonedata or color data according to a SEL signal from the control unit 108;and a data memory unit 107 for storing the image data after switchingbetween a monotone mode and a color mode according to the SEL signalfrom the control unit 108, and outputting it to the image formingapparatus.

[0048] The signal coming from the control unit 108 is transmitted to acarriage drive unit 200 to control rotating directions and speeds of thecarriage transport motors 58 and 78.

[0049] In the control circuit shown in FIG. 4, image data from the blackand white sensor 102W is used as image data in the first reading mode (amonotone reading mode), at the same time, it is determined whether it isa color original based on the output from the green sensor 102G, the redsensor 102R and the blue sensor 102B.

[0050]FIG. 5 shows an image signal control unit 100 b having three linesensors of red (R), green (G) and blue (B). The image signal controlunit 100 b includes the A/D conversion unit 103 to convert analog dataread by the three line sensors 102R, 102G and 102B into digital data;the shading correction unit 104 for correcting a shading of theconverted data (sensitivity correction between photoelectric conversionelements); a monotone mixing conversion unit 109 for producing a blacksignal based on the shading corrected data; the color detection unit 106(the determining unit) for determining a gradation of the shadingcorrected data; the control unit 108 for receiving a result determinedby the color detection unit and outputting a signal to control the imagereading apparatus; a selector unit 105 for switching and outputtingmonotone data or color data according to a SEL signal from the controlunit 108; and a data memory unit 107 for storing the image data afterswitching between a monotone mode and a color mode according to the SELsignal from the control unit 108, and outputting it to the image formingapparatus. Therefore, in the control circuit shown in FIG. 5, image datain the first reading mode (the monotone reading mode) is combined data(an AND output) from the green sensor 102G, the red sensor 102R and theblue sensor 102B. Again, based on whether there is a difference in theoutput patterns from the green sensor 102G, the red sensor 102R and theblue sensor 102B, it is possible to determine whether the original is incolor or black and white.

[0051] Similar to the case in FIG. 4, the signal from the control unit108 is transmitted to the carriage drive unit 200 to control therotating direction and the speed of the carriage transport motors 58 and78.

[0052] Therefore, the control circuit includes the color detectiondevice for determining whether it is a color document while reading ablack and white image, and the switching control device to switch thespeed of the carriage transport motors 58 and 76 between a high speedand a low speed.

[0053] A flow chart of reading control according to the first and thesecond embodiments of the present invention will be explained next.

[0054] An operator selects the reading mode (S1) shown in FIG. 6, whenthe image reading apparatus (S2) start to read an original. When thecolor reading mode is selected (S3), the image reading apparatus readsat a low speed of the color reading mode (the carriage transport motors58 and 76 drive the carriages at 25 CPM/108 mm/sec). When the monotonereading mode is selected (S5), the image reading apparatus reads at ahigh speed of the monotone reading mode (the carriage transport motors58 and 76 drive the carriage at 50 CPM/216 mm/sec). When an auto-colorselect (ACS) mode is selected (S4), the reading control described belowis executed according to the invention.

[0055]FIG. 7 shows the first control method of the image readingoperation according to the present invention. A flow chart in the FIG. 7shows the control method to determine the reading mode after reading theoriginal using the first reading mode (the reading mode whiletransporting).

[0056] In FIG. 7, the reading operation starts after placing theoriginal at a predetermined position on the platen (S10). Here, afterthe ACS mode is selected (S11), the image reading apparatus startsreading in the first reading mode (S13) when the start key is pressed(S12) on the apparatus. Data read in the first reading mode is stored(S14) in the memory as data of the first type (the black and whitedata). The stored data is converted from an analog signal of theoriginal read by the line sensors 102 into a digital signal by the A/Dconverter unit 103, as described in FIG. 4 and FIG. 5, and is processedfor the shading correction at the shading correction unit 104 and outputto the selector unit 105.

[0057] When the first reading of the original is completed (S15), thecolor detection unit 106 determines the type of stored data (S17). Whenit is determined that the data is the first type (the black and whitedata), the image data stored in the data memory 107 is output to theimage forming apparatus (S16) and the reading of the original image iscompleted.

[0058] Next, if the image data stored in the data memory 107 is thesecond type of data (the color data), the reading mode is switched fromthe first reading mode to the second reading mode (the color readingmode) to read the original at a slower speed (S18). The image data (theblack and white data) previously read in the first reading mode andstored in the data memory unit 107 as the black and white data isdeleted (S19).

[0059] Then, either the optical reading device is returned to thereading start position or to the original position that does not includethe color data (S20), and the apparatus starts reading in the secondreading mode (the color reading mode) (S21)

[0060] The second reading mode (the color reading mode) is performed ata slower speed than the first reading mode (the monotone mode). Theimage data of the original (the color image data) is stored sequentiallyin the data memory (S22). As the reading of the originals continues, theoriginal reading operations (S21 and S22) are performed. When thereading of the images on the original in the second reading mode iscompleted (S23), the color image data stored in the data memory 107 isoutput to the image forming apparatus (S24). There, if a new original isplaced on the platen, the reading operation is performed (S25 and S26).

[0061] As described in detail above, the image reading apparatus of thefirst and second embodiments are provided with the optical readingdevice for scanning a stationary original placed on a platen to readimage data; the drive device for moving the optical reading means at thefirst moving speed and the second moving speed; the detection device fordetermining a type of image data read by the optical reading means aseither the first type of data or the second type of data; the scancontrol device for obtaining and storing image data while scanning adocument at the first moving speed; and the switching control device forswitching the drive device to the second moving speed when the detectingdevice determines the image data read at the first moving speed to bethe second type of data.

[0062] The first type data is the black and white image data, and thesecond type data is the color image data. The first type is binary scaleimage data, and the second type data can also be applied to a documentincluding multiple grading color images.

[0063] According to the present invention, the image reading apparatusscans and reads the image data on the stationary original placed on theplaten. When reading the first type of original (the monotone original),the image data obtained in the initial reading operation will be used,thereby eliminating the second scanning. Therefore, it is possible toread a set of originals containing both the first type and the secondtype (the monotone and color originals) at a high speed.

[0064] In the first and the second embodiments, the image readingapparatus reads the originals placed on the platen 8 by moving theoptical reading device such as the carriages 50 and 51. In the followingdescription, an image reading apparatus has an optical reading device ata fixed position and an automatic document feeder (or ADF) fortransporting an original to the reading position to read the originalwhile moving. In FIG. 8 and the subsequent drawings, such an imagereading apparatus and image reading method will be explained as thethird and the fourth embodiments of the present invention.

[0065] Note that in the following explanation for the third and fourthembodiments, the same members are used to denote the same components andconfigurations as those in the first and the second embodiments, thusexplanations of the numbers shall be omitted for simplicity. Theexplanation will focus on the differences between the embodiments.

[0066]FIG. 8 is a sectional view showing an ADF and a reading device ofan image reading apparatus according to the third embodiment of thepresent invention. As seen in FIG. 8, the image reading apparatus of thethird embodiment of the present invention is equipped with an ADF and areading device 2. FIG. 9 shows an original transport mechanism of theADF.

[0067] An ADF 1 is mounted on the reading device 2 and transports theoriginal to a second platen 3 on the reading device 2.

[0068] The reading device 2 irradiates light from a light source 4, suchas a lamp, onto the transported original through platen 3 (FIG. 8). Thelight is reflected by a plurality of mirrors 5 and a light condensinglens 6 forms an image to be read at an image sensor, which is a readingunit such as a CCD. In other words, the second platen 3 is a readingposition (or a reading area) of the reading device 2. Also, the readingapparatus 2 is also equipped with the first platen 8 having an enougharea to cover a large document completely, as described in the first andthe second embodiments. The reading device 2 is capable of reading animage on a thick, book-like original at the first platen 8 by openingthe ADF 1 and moving the reading carriages of the first carriage 50comprising the light source 4 and the light condensing mirror 5 and thesecond carriage 51 in the sub-scanning direction.

[0069] The ADF 1 is equipped with a sheet supply tray 9 for placing aplurality of originals, a sheet supply device 10 for supplying theoriginals stacked on the sheet supply tray 9 one at a time to thereading position, and a discharge tray 11 for storing the originalsdischarged from the reading apparatus.

[0070] The ADF 1 includes a sheet supply path 16 for supplying theoriginals on the sheet supply tray 9 one at a time toward the readingposition on the second platen 3; a transport path 17 integrated with thesheet supply path 16 for guiding the originals to the second platen 3; adischarge path 18 connected to a discharge outlet on the sheet dischargetray 11 from the transport path 17; a recycling path 19 connected to aconnection portion of the sheet supply path 16 and the transport path 17from the discharge outlet on the sheet discharge tray 11 for returningthe originals to the transport path 17; an intermediate path 20 branchedfrom the discharge path 18 for guiding the original from the transportpath 17; and a switch back path 22 to switch back the originals from theintermediate path 20 and feed them in a reverse direction.

[0071] In a duplex mode to read both sides of the original, a switchback roller 40 rotates in reverse while nipping a trailing edge of theoriginal to change a transport direction of the original to switch backthe front and back sides, and sends the original to the reading positionon the second platen 3 through the recycling path 19.

[0072] Further, the ADF 1 has an idling path 80 wherein the original istemporarily inserted when the reading thereof is interrupted, thetransport of the original is stopped, the transport rollers 31 rotate inreverse, and the original is switched back and fed toward the dischargetray 11.

[0073] A document transport device in the apparatus can (re-feed) returnthe document to a predetermined reading position. In this way, a processof re-feeding the original may include returning the original to thereading position after transporting in the discharge direction, orreturning the original to the reading position after transporting theoriginal in the upstream direction opposite to the discharge direction.

[0074] As is clearly illustrated in FIG. 9, the sheet supply path 16 isprovided with a draw-out roller 26 for drawing out the original; a sheetsupply roller 28 for supplying the original drawn out by the draw-outroller 26; a separating member 29 for allowing the sheet supply roller28 to supply only the uppermost original; and a pair of resister rollers30 for feeding the original in the downstream direction after aligning aleading edge of the original supplied by the sheet supply roller 28.

[0075] The draw-out roller 26 and the sheet supply roller 28 areinterlocked to the sheet supply motor M1 via a one-way clutch OW1. Also,the resister roller 30 is interlocked to a sheet supply motor M1 via aone-way clutch OW2. The sheet supply motor M1 rotates the draw-outroller 26 and the sheet supply roller 28 with the forward rotation ofits drive shaft and rotates the resister roller 30 with the reverserotation of its drive shaft.

[0076] In the transport path 17 are arranged a large diameter transportroller 31, and a plurality of follower rollers 32, 33 and 34 pressedagainst an outer circumference of the transport roller 31. The transportroller 31 is driven by the forward and reverse driving transport motorM2.

[0077] In the discharge path 18 are arranged a follower roller 36pressed against the transport roller 31 and a pair of discharge rollers37 for discharging the originals to the discharge tray 11. The transportroller 37 is interlocked to a transport motor M2 with forward andreverse rotation capability.

[0078] Also, as described above, the switch-back path 22 is formed belowthe discharge path 18. A pair of switch-back rollers 40 located in theswitch-back path 22 is configured so that one switch-back roller 40 isaway from the other switch-back roller 40 by a pressing solenoid SOL3 sothat the original can be transported without interference when leadingand trailing edges of the original being re-fed through the recyclingpath 19 and the transport path 17 are crossed. The switch-back roller 40is interlocked to the transport motor M1 with forward and reverserotation capability.

[0079] Further, when the original detection device determines theoriginal to be a color document and to be re-read, the control deviceinstructs to stop reading the original, and to rotate the large diametertransport roller 31 in reverse to feed back the original to temporallystay in the idling path 80 disposed above the discharge path 18.

[0080] The second flapper 42 is arranged at downstream of the transportpath 17 to guide the original to either the discharge path 18 or to theswitch-back path 22. The second flapper 42 is driven by the secondsolenoid SOL 2. Also arranged above the discharge path is a flapper 43that moves upward by the trailing edge of the original fed in reverseand guides the original into the idling path. When the trailing edge ofthe original passes through, the flapper moves downward by its ownweight.

[0081] An empty sensor S1 to detect the originals on the sheet supplytray 19, a read sensor S2, a sheet discharge sensor S8 and a switch-backsensor S5 are connected to the control device (the control unit). Also,the sheet supply motor M1 and the transport motor M2 are connected tothe control device (not shown in the drawings). The pressing solenoidSOL 1, the second solenoid SOL 2 and the third solenoid SOL 3 are alsoconnected to the control device. The control device has a centralprocessing unit (or CPU) to control the transport of the original.

[0082] The control device executes the transport of the original asdescribed above by controlling each of the motors M1, M2 and each of thesolenoids SOL 1 to SOL 3 according to the output signals from each ofthe sensors S1 to S8 and the original detection device.

[0083] According to the fourth embodiment of the present invention, anADF 1 b and a reading device 2 b will be explained with reference toFIG. 10 and FIG. 11.

[0084] As shown in FIG. 10, an image reading apparatus is equipped withthe ADF 1 b and the reading device 2 b as the fourth embodiment of theapparatus. FIG. 11 shows an original transport mechanism of the ADF. ADF1 b is mounted on the reading apparatus 2 b to transport the originalsto pass over the second platen glass 3 on the image reading apparatus 2b.

[0085] An optical reading device disposed in the reading apparatus 2 bhas a light source 4, mirrors 5 a, 5 b and 5 c, a condensing lens and animage sensor 7 in the carriage 55. When reading the image data on theoriginal transported by the ADF 1 b, the carriage is positioned belowthe platen 30. The light source 4 arranged along a main scanningdirection of the original irradiates light on the original, and thelight reflected by the first mirror 5 a, the second mirror 5 b and thethird mirror 5 c is sent to the condensing lens 6. The image sensorreceives the light focused by the condensing lens 6. When reading athick original, such as a book, the optical reading device, which isprovided with the light source, mirrors, the condensing lens 6 and theimage sensor 7 in the carriage 55 as shown in FIG. 10, moves from leftto right (the sub-scanning direction) under the first platen 8 to readthe image data on the original surface.

[0086] An operational control of the carriage 55 is as described for thesecond embodiment. The image data, which is the light received by theimage sensor, is converted to a digital signal in the reading device 2 band then sent to an image forming apparatus G, such as a copier.

[0087] The ADF 1 b is equipped with a sheet supply device for drawingout the originals stacked on the sheet supply tray 9 one at a time tosupply the originals in a determined sheet supply direction; a transportdevice positioned below the sheet supply tray 9 for passing theoriginals over the second platen 3 in the image reading portion whilerotating the originals; and a discharge device for discharging theoriginals after passing the second platen 3 to the discharge tray 11.Also, the ADF 1 b is supported to be able to rotate at the downstreamside of the direction of sheet supply. The two drive motors M1 and M2drive the sheet supply device, the transport device and the dischargedevice (See FIG. 11).

[0088] Further, the ADF 1 b has the sheet supply path 16 for supplyingthe originals stacked on the sheet supply tray 9 one at a time towardthe reading position on the second platen 3, the transport path 17integrated with the sheet supply path 16 for guiding the original to thesecond platen 3, and the discharge path 18 connected from the transportpath 17 to the discharge outlet of the discharge tray 11.

[0089] In the sheet supply path 16 are arranged the draw-out roller 26for drawing out the originals, the sheet supply roller 28 for supplyingthe originals drawn out by the draw-out roller 26, the separating member29 for allowing the sheet supply roller 28 to supply only the uppermostoriginal, and a pair of the resister rollers 30 for feeding the originalsupplied by the sheet supply roller 28 after aligning the leading edgethereof.

[0090] The draw-out roller 26 and the sheet supply roller 28 areinterlocked to the sheet supply motor M1 via the one-way clutch OW1.Also, the resister roller 30 is interlocked to the sheet supply motor M1via the one-way clutch OW2. The sheet supply motor M1 rotates thedraw-out roller 26 and the sheet supply roller 28 with the forwardrotation of its drive shaft and rotates the resister roller 30 with thereverse rotation of its drive shaft.

[0091] In the transport path 17 are arranged the transport rollers 39 aand 39 b. The transport motor M2 drives the transport rollers 39 a and39 b in the forward and reverse driving.

[0092] The discharge roller 37 is interlocked to the transport motor M2.When the duplex mode is selected to read both sides of the original, thedischarge roller 37 rotates in reverse while nipping the trailing edgeof the originals to switch-back the original and send it to thetransport path 17 via the recycling path 19. A pair of the dischargerollers are configured so that one discharge roller 37 is away from theother discharge roller 37 by the pressing solenoid SOL1 so that theoriginal can be transported without interference when the leading andtrailing edges of the original recycled through the recycling path 19and the transport path 17 cross. Also, the discharge path 18 and thepaired discharge rollers 37 have the switch-back function to switch thedirection of the originals from front to back.

[0093] When the original detection device determines a type of originaland it is necessary to re-read the original (for example when switchingfrom the monotone reading mode to the color reading mode), the controlmeans stops the reading of the original and transports it to thedischarge path 18. The original transported to the discharge path 18 istransported again to the second platen 3 by switching it in therecycling path 19, via the transport path 17. The back and front sidesof the original transported again in this manner are now inverted toread the backside of the original. For that reason, in order to read asurface of the original when interrupted, the original is transportedfrom the transport path again to the discharge path to be switched backand fed back to the reading position on the second platen 3 via therecycling path 19. In this way, the original is transported and set atthe reading position on the second platen 3 to be read at a controlspeed (for example the slower speed in the color reading mode).

[0094] The empty sensor (not shown in the drawings), the read sensor S2,the discharge sensor (not shown in the drawings), and the switch-backsensor (not shown in the drawings) are connected to the controlapparatus (the control unit). Also, the supply motor M1 and thetransport motor M2 are connected to the control apparatus (not shown inthe drawings). The pressing solenoid SOL 1 is also connected to thecontrol apparatus. The control apparatus has a central processing unit(or CPU) to control the transport of the original.

[0095] The control apparatus executes the transport of the original bycontrolling each of the motors of M1, M2 and the solenoid SOL 1according to the output signals from the sensor S2 and the originaldetection device.

[0096] As explained for the first and the second embodiments in FIG. 3,to determine whether the image read is in monotone or color, thewavelengths from each of the line sensors are checked to be different orto be uniform. In the same way as described according to FIG. 3, it ispossible to determine based on the image data read at the high speed inmonotone reading mode.

[0097] In this way, the color detection unit (the determining unit) inthis invention is configured to receive an output from a shadingcorrection unit (described later) converted into a digital signal at thered, green and blue line sensors. When there is a difference in theoutput patterns from the sensors, it is determine to be a colordocument. In the case of no difference, it is determined to be a blackand white document.

[0098] As shown in FIG. 4 and FIG. 5, the image-signal control apparatus(hereinafter referred to as a control apparatus) is provided a datamemory unit 107 (FIG. 12 and FIG. 13) to sequentially store image dataread by the reading device.

[0099] Depending on the type of image reading apparatus, it is possibleto output image data from the reading means, without a data memory tostore the image data, to an image forming apparatus after processingcorrection of the image data. In such a case, in applying the invention,the detection device uses the processed signal of the image data fromthe reading means to determine whether the image data is in monotone orcolor.

[0100]FIG. 12, substantially the same as FIG. 4, shows the circuitconfiguration of a control apparatus 100 having four line sensors,namely three line sensors of red (R), green (G) and blue (B) and a blackand white (B/W) sensor. The control apparatus 100 shown in FIG. 4includes an A/D conversion unit 103 to convert analog data read by thefour line sensors 102W, 102R, 102G and 102B into digital data; a shadingcorrection unit 104 for correcting a shading of the converted data(sensitivity correction between photoelectric conversion elements); acolor detection unit 106 (a determining unit) for determining agradation of the shading corrected data; a control unit 108 forreceiving a result determined by the color detection unit and outputtinga signal to control the image reading apparatus; a selector unit 105 forswitching and outputting monotone data or color data according to a SELsignal from the control unit 108; and a data memory unit 107 for storingthe image data after switching between a monotone mode and a color modeaccording to the SEL signal from the control unit 108, and outputting itto the image forming apparatus.

[0101] The signal coming from the control unit 108 is transmitted to acarriage drive unit 200 to control rotating directions and speeds of thecarriage transport motors 58 and 78.

[0102]FIG. 13 shows the image signal control unit 100 b having threeline sensors of red (R), green (G) and blue (B). The image signalcontrol unit 100 b includes the A/D conversion unit 103 to convertanalog data read by the three line sensors 102R, 102G and 102B intodigital data; the shading correction unit 104 for correcting a shadingof the converted data (sensitivity correction between photoelectricconversion elements); a monotone mixing conversion unit 109 forproducing a black signal based on the shading corrected data; the colordetection unit 106 (the determining unit) for determining a gradation ofthe shading corrected data; the control unit 108 for receiving a resultdetermined by the color detection unit and outputting a signal tocontrol the image reading apparatus; a selector unit 105 for switchingand outputting monotone data or color data according to a SEL signalfrom the control unit 108; and a data memory unit 107 for storing theimage data after switching between a monotone mode and a color modeaccording to the SEL signal from the control unit 108, and outputting itto the image forming apparatus. Therefore, in the control circuit shownin FIG. 13, image data in the first reading mode (the monotone readingmode) is combined data (an AND output) from the green sensor 102G, thered sensor 102R and the blue sensor 102B. Again, based on whether thereis a difference in the output patterns from the green sensor 102G, thered sensor 102R and the blue sensor 102B, it is possible to determinewhether the original is in color or black and white.

[0103] Similar to the case in FIG. 13, the signal from the control unit108 is transmitted to the carriage drive unit 200 to control therotating direction and the speed of the carriage transport motors 58 and78.

[0104] A flow chart of reading control according to the embodiment ofthe present invention will be explained next.

[0105] An operator selects the reading mode (S1) shown in FIG. 14, whenthe image reading apparatus (S2) start to read an original. When thecolor reading mode is selected (S3), the image reading apparatus readsat a low speed of the color reading mode (25 CPM/108 mm/sec). When themonotone reading mode is selected (S5), the image reading apparatusreads at a high speed of the monotone reading mode (50 CPM/216 mm/sec).When an auto-color select (ACS) mode is selected (S4), the readingcontrol described below is executed according to the invention.

[0106]FIG. 15 shows the second control method of the image readingoperation according to the present invention. A flow chart shows thecontrol method to determine the reading mode after reading the originalusing the first reading mode (the reading mode while transporting).

[0107]FIG. 16 shows the third control method of the image readingoperation according to the present invention and shows a flow chart ofthe control method to determine the reading image data mode whilereading the original

[0108] In FIG. 14, the reading operation starts after placing theoriginal at a predetermined position on the platen (S10). Here, afterthe ACS mode is selected (S11), the image reading apparatus startsreading in the first reading mode (S13) when the start key is pressed(S12) on the apparatus. Data read in the first reading mode is stored(S14) in the memory as data of the first type (the black and whitedata). The stored data is converted from an analog signal of theoriginal read by the line sensors 102 into a digital signal by the A/Dconverter unit 103, as described in FIG. 12 and FIG. 13, and isprocessed for the shading correction at the shading correction unit 104and output to the selector unit 105.

[0109] When the first reading of the original is completed (S15), thecolor detection unit 106 determines the type of stored data (S17). Whenit is determined that the data is the first type (the black and whitedata), the image data stored in the data memory 107 is output to theimage forming apparatus (S16) and the reading of the original image iscompleted. Then, the original is discharged to the discharge path 18.

[0110] Next, if the image data stored in the data memory 107 is thesecond type of data (the color data), the reading mode is switched fromthe first reading mode to the second reading mode (the color readingmode) to read the original at a slower speed (S18). The image data (theblack and white data) previously read in the first reading mode andstored in the data memory unit 107 as the black and white data isdeleted (S19). Then, the original is transported again to the readingposition 3 by the transport roller 31 (S20). The operation can be doneby recycling through the recycling path 19 or by feeding back in thedirection opposite to the discharge direction.

[0111] When the original is returned to the reading position 3, theoriginal starts to be read at the slower speed of the second readingmode (the color reading mode) (S21). The image data on the original (thecolor image data) are stored sequentially in the data memory (S22).While reading the originals, the original reading operations (S21 andS22) continue. When reading the image on the original by the secondreading mode is completed (S23), the color image data stored in the datamemory 107 are output to the image forming apparatus (S24). The readingoperation control is performed for all originals stacked on the sheetsupply tray 9 (S25 and S26).

[0112]FIG. 16 is an example of the third image reading operation controlof the present invention. Here, differing from the second controlmethod, the invention determines whether the data is in monotone orcolor while reading the original.

[0113] In FIG. 10, the reading operation starts after placing theoriginal at a predetermined position on the platen (S30). Here, afterthe ACS mode is selected (S31), the image reading apparatus startsreading in the first reading mode (S33) when the start key is pressed(S32) on the apparatus. Data read in the first reading mode is stored(S34) in the memory as data of the first type (the black and whitedata). The stored data is converted from an analog signal of theoriginal read by the line sensors 102 into a digital signal by the A/Dconverter unit 103, as described in FIG. 12 and FIG. 13, and isprocessed for the shading correction at the shading correction unit 104and output to the selector unit 105.

[0114] Next, in the example of the third image reading operationcontrol, which is different from the example of the second image readingoperation control, it is determined whether the image data sequentiallyread while reading the images on the original is the first type (theblack and white data) or the second type (the color data) (S35). When itis determined that the data is the first type (the black and whitedata)(S36), it is continued to read in the first reading mode. When itis determined that all the data is the first type (the black and whitedata), the image data stored in the data memory 107 is output to theimage forming apparatus (S38) and the reading of the original image iscompleted. Then, the original is discharged to the discharge path 18.

[0115] When the image data on the original is determined to be thesecond type of data (the color data) (S35), the reading in the firstreading mode is stopped (S37). The apparatus switches from the firstreading mode to the second reading mode (the color reading mode) to readthe color original at the slow speed (S39). The image data (the blackand white data), which is read in the first reading mode and stored inthe data memory unit 107 as black and white data, is deleted (S40).

[0116] Then, the original is returned to the predetermined readingposition by the transport roller 31 (S41). The operation can be done byrecycling through the recycling path 19 or by feeding back in thedirection opposite to the discharge direction.

[0117] When the original is returned to the reading position 3, theoriginal starts to be read at the slower speed of the second readingmode (the color reading mode) (S42). The image data on the original (thecolor image data) are stored sequentially in the data memory (S43).While reading the originals, the original reading operations (S21, S22and S23) continue until the end. When reading the image on the originalby the second reading mode is completed (S44), the color image datastored in the data memory 107 are output to the image forming apparatus(S45). When a single sheet of the original is completed to read, thecolor image data stored in the data memory 107 are output to the imageforming apparatus (S24). The reading operation control is performed forall originals stacked on the sheet supply tray 9 (S27).

[0118] Thus, according to the third and fourth embodiments of thepresent invention, the image reading apparatus is provided with theoptical reading device disposed at the predetermined reading positionunder the platen for reading the original moving on the platen; thetransport device capable of re-feeding the same original to the readingposition; the detecting device for determining the type of image data onthe original read by the optical reading device; and the control devicefor control the other devices. The control device controls the otherdevices such that when the image data is the first type, the image datausing the first reading mode is output. Further, when the image data isthe second type, the original is transported (re-fed) to the readingposition again to be read the image data using the second reading modethat is different from the first reading mode.

[0119] According to the present invention, the image reading apparatusreads the image data on the original being transported by the ADF. Whenreading the first type of original, for example a monotone original, theimage data obtained in the initial reading operation will be used,thereby eliminating the second scanning. Therefore, it is possible toread a set of the originals containing both monotone originals and colororiginals at a high speed. Also, according to the present invention,both when reading the original using the ADF and when reading theoriginal placed stationary on the platen 8, the black and white imagesare read while determining the type of originals. Thus, only when thecolor original is read in the color reading mode again, so it ispossible to read the originals at higher processing speeds.

[0120] While the invention has been explained with reference to thespecific embodiments of the invention, the explanation is illustrativeand the invention is limited only by the appended claims.

What is claimed is:
 1. An image reading apparatus for reading an imageon an original, comprising: a platen for placing the original; readingmeans arranged under the platen for reading the original placed on theplaten to create image data; drive means connected to the reading meansfor moving the same at one of a first moving speed and a second movingspeed; detection means electrically connected to the reading means fordetermining whether the image read by the reading means is a first kindof data or a second kind of data; and control means electricallyconnected to the reading means and the detection means for controllingthe same so that the reading means continues to read the original at thefirst moving speed when the image data read at the first moving speed isdetermined to be the first kind of data, and the reading means reads theoriginal at the second moving speed when the image data read at thefirst moving speed is determined to be the second kind of data.
 2. Animage reading apparatus according to claim 1, wherein said control meansincludes scanning control means for storing the image data read at thefirst moving speed, and switching control means for switching thedriving means to the second moving speed when the detection meansdetermines the image data read at the first moving speed to be thesecond kind of data.
 3. An image reading apparatus according to claim 2,wherein said first moving speed is faster than the second moving speed.4. An image reading apparatus according to claim 2, wherein said firstkind of data is monotone image data, and said second kind of data isdata including color image data.
 5. An image reading apparatus accordingto claim 1, wherein said reading means includes a monotone image datareading mode for reading the image at the first moving speed, and acolor image data reading mode for reading the image at the second speed,said control means controlling such that when the image data read at thefirst moving speed is determined to be monotone image data, the readingmeans continues to read the original at the first moving speed for themonotone image data reading mode, and when the image data read at thefirst moving speed is determined to be color image data, the readingmeans stops reading the original at the first moving speed, returns to afirst reading position or position of the original where an image isonly in monotone, and starts to read the image data at the second movingspeed for the color image data reading mode.
 6. An image reading methodfor reading an image on an original on a platen of an image readingapparatus, comprising the steps of: reading said original in a firstreading mode to obtain image data; determining said image data to be oneof a first kind of data and a second kind of data; outputting said imagedata when the image data is determined to be the first kind of data; andreading said original in a second reading mode when the image data isdetermined to be the second kind of data.
 7. An image reading methodaccording to claim 6, wherein when the image data is determined to bethe second kind of data, reading is returned to a first reading positionor position of the original where an image is only in monotone and theimage date is read at the second reading mode slower than the firstreading mode.
 8. An image reading apparatus for reading an image on anoriginal, comprising: a platen for placing the original, reading meansarranged at a predetermined reading position under the platen forreading the original placed on the platen to obtain image data in one ofa first reading mode and a second reading mode; transport means disposedadjacent to the platen for transporting the original and being capableof returning the original to the platen; detection means electricallyconnected to the reading means for determining whether the image dataread by the reading means is a first kind of data or a second kind ofdata; and control means electrically connected to the reading means, thetransport means and the detection means, said control means operatingthe transport means for ejecting the original and outputting the imagedata read in the first reading mode when the detection means determinesthe image data to be the first kind, and operating the transport meansto return the original to the platen and actuating the reading means toread in the second reading mode when the detection means determines theimage data to be the second kind.
 9. An image reading apparatusaccording to claim 8, wherein said transport means re-circulates theoriginal to the platen to return to the reading position after thetransport means transports the original downstream when the detectionmeans determines the image data to be the second kind.
 10. An imagereading apparatus according to claim 8, wherein said transport meansreturns the original to the reading position on the platen bytransporting the original upstream when the detection means determinesthe image data to be the second kind.
 11. An image reading apparatusaccording to claim 8, wherein said transport means has a first movingspeed at the first reading mode, and a second moving speed at the secondreading mode for transferring the original less than that of the firstmoving speed.
 12. An image reading apparatus according to claim 8,wherein said reading means reads a monotone image in the first readingmode, and reads a color image in the second reading mode.
 13. An imagereading apparatus according to claim 8, wherein said reading means readsa binary scale image in the first reading mode, and reads a multiplescale image in the second reading mode.
 14. An image reading apparatusaccording to claim 12, wherein said control means operates such thatwhen the detection means is determined that the image being read is thecolor image while the reading means is reading the image at a monotoneimage mode as the first reading mode, the reading means stops readingthe original at the monotone image mode; the original is supplied againon the platen; and the reading means reads the image as a color imagereading mode.
 15. An image reading method for reading an image on anoriginal placed on a platen of an image reading apparatus, comprisingthe steps of: initially reading said original in a first reading mode toobtain image data; determining a kind of image to be one of a first kindof data and a second kind of data; outputting said image data of thefirst reading mode and discharging the original when the image data isdetermined to be the first kind of data; and returning the original tothe platen and secondarily reading the same in a second reading modedifferent from the first reading mode when the image data is determinedto be the second kind of data.
 16. An image reading method according toclaim 15, wherein said returning step includes the step ofre-circulating the original after transporting the original downstream,and the step of supplying the original again to the platen.
 17. An imagereading method according to claim 15, wherein said returning stepincludes the step of transporting the original upstream opposite to adischarge direction, and the step of returning the original to theplaten.
 18. An image reading method according to claim 15, wherein areading speed in the first reading mode is greater than that in thesecond reading mode.
 19. An image reading apparatus according to claim15, wherein said initial reading step reads a monotone image in thefirst reading mode, and said second reading step reads a color image inthe second reading mode.
 20. An image reading method according to claim19, wherein when the image being read is the color image while the imageis being read at the monotone image, said returning step include thestep of stop-reading the original at the monotone image; the step ofreturning the original again on the platen; and the step of reading as acolor image reading mode.